   (js/console.log "re-render")
   (let [[data set-data] (use-state [])
         [selected set-selected] (use-state nil)
-        print-duration
-        (fn print-duration []
-          (stop-measure))
         run
         (fn run [_]
-          (start-measure "run")
           (set-data (vec (u/build-data id-atom 1000)))
           (set-selected nil))
         run-lots
         (fn run-lots [_]
-          (start-measure "runLots")
           (set-data (vec (u/build-data id-atom 10000)))
           (set-selected nil))
         add
         (fn add [_]
-          (start-measure "add")
           (set-data u/add id-atom))
         update-some
         (fn update-some []
-          (start-measure "update")
           (set-data u/update-some))
         clear
         (fn clear []
-          (start-measure "clear")
           (set-selected nil)
           (set-data []))
         swap-rows
         (fn swap-rows []
-          (start-measure "swapRows")
           (set-data u/swap-rows))
         select
         (fn select [id]
-          (start-measure "select")
           (set-selected id))
         delete
         (fn delete [id]
-          (start-measure "delete")
           (set-data u/delete-row id))]
-    (use-effect :always
-      (print-duration))
     (d/div
      {:class "container"}
      (d/div

            ["react-dom" :as rdom]
            [demo.utils :as u]))

(def start-time (atom nil))
(def last-measure (atom nil))

(defn start-measure [name]
  (reset! start-time (.now js/performance))
  (reset! last-measure name))

(defn stop-measure []
  (if-let [last @last-measure]
    (.setTimeout js/window
                 (fn []
                   (reset! last-measure nil)
                   (let [stop (.now js/performance)]
                     (.log js/console (str last " took " (- stop @start-time)))))
                 0)))


(defnc row [{:keys [data selected? on-click on-delete]}]
  (d/tr {:class (if selected? "danger")}
    (d/td {:class "col-md-1"}
          (:id data))
    (d/td {:class "col-md-4"}
          (d/a {:on-click (fn [e] (on-click (:id data)))}
               (:label data)))
    (d/td {:class "col-md-1"}
     (d/a {:on-click (fn [e] (on-delete (:id data)))}

      (d/div
       {:class "row"}
       (d/div {:class "col-md-6"}
              (d/h1 (str "Helix")))
       (d/div {:class "col-md-6"}
              (d/div {:class "row"}
                     (d/div {:class "col-sm-6 smallpad"}
